(i) Reduce 3cos x + 4sin x to the form R cos (x – α). Where R 0 and 0

Question

(i) Reduce 3cos x + 4sin x to the form R cos (x – α). Where R > 0 and
 
 	0 < α < 90.									[4 marks]

           Hence

	(ii) Solve the equation 3cos x + 4sin x  = 1.5 for 0 < x < 360.    	[4 marks]

(iii) Find the maximum value of 3cos x + 4sin x and the value of x for which it 

occurs. 	

Deduce the minimum value of 	3/5+(3cosx+4sinx)

aravindg · Answer

try this cos alpha=3/5 ,sin alpha= 4/5

3cos x + 4sin x=5(3/5 cos x+4/5 sin x )

anonymous · Answer

i need the answer for the third question..deduce the minimun value.Help me plzz

e.mccormick · Answer

Calculus? Do derivative tests. I have to go soon, but here is a nice overview: http://tutorial.math.lamar.edu/Classes/CalcI/MinMaxValues.aspx

e.mccormick · Answer

The main poin is that if the slope of a tangent line is 0, then the curve is at a minimum or a maximum.  So once you have the point, you check to see if things increase up to it an down away from it, a max, or other way around, a min.

e.mccormick · Answer

If it is trig, graph it, look at the period, and find the point where it is highest based on the period.